The present invention relates to techniques for monitoring the medical condition of a subject or subject/patient most especially neuromuscular motor activity, and, to a method and apparatus for monitoring a subject or subject/patient at a remote site from a central station by means of interactive visual, audio and data transmission communications. While the invention is also suitable for use in any situation where any subject or subject/patient is to be monitored at a site remote from a central station, an important application is the monitoring and caring for the elderly (both well and ill persons) in the home environment. Thus, the present invention can also be said to relate to the field of geriatric care. Further, the techniques disclosed may also be utilized in a hospital or clinic setting inasmuch as they constitute diagnostic techniques useful for any person and at any local or remote location. Additionally the techniques and methods have application to other disciplines including, but not limited to, psychological diagnosis and monitoring, and interrogation monitoring and analysis. Finally, the invention enables conduct of physiological analysis utilizing a single video camera and without markers.
Ambulatory Care in General
Most of the resources for modern medicine have been invested in the development of highly sophisticated hospital facilities. Therefore, institutional patient care has become prohibitively expensive, in many cases overused and for a substantial number of patients potentially harmful. The tendency to substitute costly institutional patient care with effective and cost containing extra-institutional, ambulatory medical facilities is gaining rapid momentum. These attempts however are still confined to the delivery of care in outpatient clinics to which the patient has to come to obtain medical care, or home nurse visits which are short, scarce, and insufficient. The combination of growing sophistication in ambulatory monitoring technology together with the explosive development of telecommunication provides the ideal substrate to enable the development of highly sophisticated, reliable and affordable, remotely controlled, remote monitoring capabilities which can monitor, analyze and assess many physiological parameters in any potential subject and in any possible location. Such a system is specially suited to provide a sophisticated platform or home care facilities for a wide spectrum of subject/patient.
The described invention is a neuromuscular and motor activity remote monitoring system for any person in need of remote assessment of physiological, psychological, and other parameters. From the subject/patient care aspect one of the important applications of this system is monitoring and care of the elderly geriatric population. This is due to the complexity of the holistic approach to geriatric care, which will be elaborated below.
Geriatric Ambulatory Home Monitoring
Modern society with its improvement in living conditions and advanced health care has brought about a marked prolongation of life expectancy. This change has resulted in a dramatic and progressive increase in the geriatric population. A large percentage of the geriatric population needs continuous general, as well as medical, supervision and care. For example, supervision of daily activities such as dressing, personal hygiene, eating and safety as well as supervision of their health status is necessary. Furthermore, the relief of loneliness and anxiety is a major, yet unsolved, problem to be addressed. These and other facets of the management of the ever increasing geriatric population have yet to be successfully addressed and solved.
The creation of retirement facilities and old age homes, as well as other geriatric facilities, provide only a partial solution to the problems facing the geriatric population. The geriatric population, a constantly increasing fraction of society, has become increasingly dependent upon the delivery of home health and general care, which has its own set of challenges and drawbacks.
The notion of ambulatory (home environment) subject/patient care is gaining increased popularity and importance. This shift in subject/patient care from the xe2x80x9cshelteredxe2x80x9d institutional milieu to the subject/patient""s home, work place, or recreational environment is due primarily to a radical change in concepts. That is, specialists in geriatric care now tend to keep the aged in their own natural environment for as long as possible.
Except for scarce model organizations, home care is still carried out either by the subject/patient""s family or by nonprofessional help, or, in the usual circumstance, by professional, highly trained personnel at very significant expense. The monitoring equipment at home care facilities is usually minimal or nonexistent, and the subject/patient has to be transported to the doctor""s office or other diagnostic facility to allow proper evaluation and treatment.
Subject/patient follow-up is presently done by means of home visits of nurses which are of sporadic nature, time consuming and generally very expensive. A visiting nurse can perform about 5-6 home visits per day. The visits have to be short and can usually not be carried out on a daily basis. Moreover, a visiting nurse program provides no facilities for continuous monitoring of the subject/patient and thus no sophisticated care, except in fortuitous circumstances, in times of emergency. The remainder of day after the visiting nurse has left is often a period of isolation and loneliness for the subject/patient. The existing home care nursing facilities divert skilled nurses, a scarce commodity, from the hospital environment and uses them in a highly inefficient manner due to the wide dispersion of the subject/patients and the lack of sophisticated diagnostic facilities in the subject/patient""s home. Clearly, the practice of visiting nurses leaves much to be desired.
These considerations apply to the general population as well, as the spiraling cost of hospital care has lead to a dramatic increase in the use of outpatient care as a treatment modality.
Falls and Injuries in the Aged
Additional facts support development of an improved home health care system especially for a geriatric population. In particular, falls are a major health problem among the elderly, causing injury, disability and death. One third (some studies suggest half) of those over the age of 65 suffer at least one fall each year. The rate of falling increases to 40% among those who exceed the age of 80. According to the National Safety Council, falls accounted for one-third of the death total for the elderly. Those who survive falls may have restricted activity, soft-tissue injuries, or fractures. It is estimated that up to 5% of falls by elderly persons result in fractures. A similar percent result in soft-tissue injury requiring hospitalization or immobilization for an extended period. It is estimated that hip fractures resulting from falls cost approximately $2 billion in the United States during 1980. Falls are mentioned as a contributing factor to admissions to nursing homes.
The factors leading to falls can be divided into two main groups: environmental factors and medical factors. In spite of the difficulty in the surveillance of subject/patient condition before a fall, almost all researchers share the conclusion that environmental hazards are decreasingly important in causing falls as age increases. A clear correlation between clinical or medical problems and the incident of falls by the elderly has been established. Many of these medical problems of the elderly or infirm can be detected by simple clinical observation. For example gait and balance abnormality may indicate difficulty with neurologic and musculoskeletal functions that may contribute to physical instability. Changes in gait can be identified by the following: slow speed, short step length, narrow stride width, wide range of stepping frequency, a large variability of step length, and increasing variability with increasing frequency.
Thus, there are relatively straightforward techniques that enable diagnosis of a predisposition or likelihood of falls among the elderly. U.S. Pat. Nos. 5,441,047 and 5,544,649 (xe2x80x9cthe ""047 and ""649 patentsxe2x80x9d) disclose inexpensive procedures for undertaking such diagnoses or investigating such predispositions in a large subject/patient population wherein the kinematic condition of the subject/patient can be investigated or where the appearance, and reflex activity of the subject/patient can be investigated with ease. In particular, the ""047 and ""649 patents describe an ambulatory (in the home) subject/patient health monitoring system wherein a health care worker at a central station monitors the subject/patient, while the subject/patient is at a remote location. The subject/patient may be a person having a specific medical condition being monitored or may be an elderly person desiring general medical surveillance in the home environment. Video transmission cameras are provided at the subject/patient""s remote location and at the central station such that the subject/patient and the health care worker are in interactive visual and audio communication. A communications network such as an interactive cable television is used for this purpose. Various medical condition sensing and monitoring equipment are placed in the subject/patient""s home, depending on the particular medical needs of the subject/patient. The subject/patient""s medical condition is measured or sensed in the home and the resulting data is transmitted to the central station for analysis and display. The health care worker then is placed into interactive visual communication with the subject/patient concerning the subject/patient""s general well being, as well as the subject/patient""s medical condition. Thus, the health care worker can make xe2x80x9chome visitsxe2x80x9d electronically, twenty-four hours a day, seven days a week in a non-intrusive, cost effective, privacy protecting manner.
Prior Art Testing Techniques
While the ""047 and ""649 patents (incorporated herewith by reference) represent an improvement over prior art techniques, additional testing methods are needed to properly and fully exploit the opportunities provided by remote diagnostic systems as well as hospital or clinic site diagnosis. The common approach to functional testing of the motor ability of elderly persons is based on scoring the performance of complex functional tests such as xe2x80x9cGet Up and Goxe2x80x9d, xe2x80x9cFregley Ataxia Test Batteryxe2x80x9d and others. The resulting score is used for estimating the risk of falling, mainly, for purposes of epidemiological studies. Each test consists of a set of simple motor tasks. For clinical decision-making, physicians generally take into account the results of the separate tasks, instead of the resulting score of the whole test. It is known that the ability to perform a simple motion task is directly connected with concrete medical conditions of a subject/patient whereas the resulting score only provides a general impression. These tests very often require special equipment (e.g., static and dynamic force plates with or without feedback, markers on specific body locations, and 6 to 10 meters of walkway etc.). Moreover these tests require the presence of an assistant to guide the test and insure the accuracy and safety of its performance. As a rule, such testing can only be realized in a clinic that has the required equipment and a sufficiently skilled staff. Likewise, such testing is too expensive for everyday practice, usually cannot be repeated as often as necessary and therefore cannot be used to perform thorough monitoring of elderly subject/patients with restricted capacities to visit clinics.
U.S. Pat. No. 5,980,429 (xe2x80x9cthe ""429 patentxe2x80x9d) describes a monitoring technique for training programs where effectiveness of training is assessed through a thorough comparison of quantitative and qualitative measured parameters with quantitative and qualitative benchmark data. Qualitative parameters relate to the accuracy of performing the tasks and quantitative parameters to a number of successive performances in a certain period of training. To obtain a sequence of qualitative benchmark data, training tasks are arranged by level of difficulty of performance. The measured results of a given task are categorized according to the completeness and accuracy of its performance. Thus a system for objective assessment is realized. Benchmark data are defined from previous subject""s performances or from data derived from corresponding reference groups. The xe2x80x9cSew Balance Masterxe2x80x9d test for assessment of motor and balance ability of a subject/patient described in the ""429 patent is a typical example of a well-designed clinical test. The training program is intended for persons with an intact central nervous system, i.e., can only be applied in specific injuries. Moreover, the assessment always relates to a person that does his hardest exercises on his own highest level. Hence the arrangement of the motor tasks by degree of difficulty may be adequate even if the accuracy of the assessment is restricted by dividing the results of measurements over 3 to 5 categories.
However, an elderly subject performing tasks in accordance with such testing schemes, without any assistant, will mostly carry out the tasks on a far lower level than his or her maximum abilities. So, the tasks should be designed with a degree of difficulty but free from essential muscle tension and unstable poses that could lead to a fall. Moreover, nervous and physiological disorders, often present in elderly persons, necessitate individual tailoring of the difficulty level of the tests. Taking into account the fact that in elderly persons many essential disorders, associated with motor difficulties, evolve very gradually, the monitoring system should be able to detect small trend changes in motor behavior of the subject/patient.
Thus, it can be seen that techniques leveraging the availability of video image data, i.e., that build upon and improve the teachings of the ""047 and ""649 patents, would be an important advancement of the art. Furthermore, testing methodologies, including testing contents and protocols should take advantage of these advances, thereby maintaining and improving the diagnostic reliability of current medical techniques.
The present invention is directed to improvements to the interactive video and audio subject/patient monitoring system disclosed in the ""047 and ""649 patents by providing a video processing technique whereby motion characteristics are readily discerned from video image data of a subject/patient. (The term xe2x80x9csubject/patientxe2x80x9d as used herein is to be interpreted broadly to include elderly persons, persons actively being treated or monitored for specific medical ailments, as well as persons who need to have their general medical condition and gait and balance status monitored by practitioners for any reason, for example: astronauts in space stations etc. Additionally, persons who are being monitored for psychological condition, mood, truth telling and general physical condition are considered subject/patients. By way of example, but not limitation, interrogation techniques which rely upon physical response to evince truthfulness or falsehood may utilize variations of the techniques disclosed herein along and in combination with other physical response measurements such as respiration, heart rate, etc.) Furthermore, the present invention sets forth a system of motor tasks and protocols for their execution that is particularly adapted for use in the interactive television and audio monitoring system as well as being useful at a hospital or clinic site where clinicians work directly with subject/patients or any other remote monitoring scenario. An example of a series of diagnostic tests is disclosed wherein the tests are susceptible of qualitative, quantitative and/or image processing review and analysis. The term xe2x80x9cmedicalxe2x80x9d herein is broadly inclusive of physical, psychological and behavior conditions by way of example.
The image processing techniques enable diagnosis associated with skeletal and muscular movement in a highly quantitative and recordable manner. Thus, the video image of the patient performing each of the tasks in the protocol is captured by a video acquisition system. The video image data is received in the form of a sequence of equally spaced (in the time domain) images. The acquired images are then compressed using standard image compression techniques such as that defined by MJPEG compressed images in order to reduce the data content to allow storage on a local disk or to allow transmission to a remote location. Unlike neuromuscular motor activity measured in standard gait and balance laboratories which require a multitude of cameras and require that markers be placed on the patient, the present invention, without limiting it, produces adequate results with the use of a single camera and without the use of markers.
A pre-processing element follows the image acquisition. The purpose of the preprocessing element is to remove the background and produce a sequence of silhouette images or outline images of the patient on a frame-by-frame or field-by-field basis by applying a sequence of standard image processing operations on the acquired images. The image processing operations, well known in the art, include contrast control, brightness control, segmentation and edge detection. The pre-processing sequence of operations may be manually defined by an operator of the system or automatically discovered through the use of quality indicators and feedback to search for the best set of operations.
The pre-processing may be performed at the central location or at the remote location in a distributed system. The result of the pre-processing is a plurality of matrices (one per frame or field of the original video image sequence) containing the silhouette or outline image. In the case where the pre-processing is performed at the patient location, the resultant pre-processed file is transferred to the central facility for continued post processing.
A post-processing element follows the pre-processing. The purpose of the post-processing is to make measurements of various parameters of the silhouette or outline of the patient on a frame-by-frame or field-by-field basis. The aforementioned parameters or mathematical combinations of these parameters represent physiological indices associated with gait and balance as with other neuromuscular motor activities. An example of a measured parameter in the space domain is the maximum height that a patient""s foot is raised from the floor. An example of a measured parameter in the time domain is the time it takes a patient to complete a cycle while walking.
The results of the measurements from the post-processing are stored for long-term to monitoring and trending. The system provides for the definition of predefined normal value ranges for the results as well as adaptive individual normal value ranges based on the historical data from a particular patient An alarm notification is provided when a value falls outside the expected normal range.
A graphical xe2x80x9cfinger printxe2x80x9d of the patients walking pattern is obtained by summing the is individual matrices provided from the output of the pre-processing and storing the result in a resultant matrix. This is similar to placing each outline from a single frame onto a transparency and placing the transparencies one on top of the other. The resulting picture provides a unique characteristic template of the patient that may be analyzed and compared to previously stored templates of the patient. Changes from the normal historical pattern represent changes in the neuromuscular motor activity of the patient that may be indicative of physiological problems.
An integral part of this invention is the protocols used to test the patient. Each protocol is an action or a plurality of actions that the patient must perform. Some of the protocols such as walking in a straight line or walking in place produce direct physiological protocols produce the indirect physiological information such as the ability to complete a sequence of balance tasks each of which are subsequently more difficult resulting in a numerical grade. The combined tests are designed to elicit all necessary physical and neurological information relating to a patient""s ability to perform neuromuscular motor tasks. The tasks are particularly chosen to maximize safety and to minimize the probability of the patient falling down or otherwise losing balance when performing the tasks. To this end, tasks are preferably ordered by difficulty within certain tests. The level of difficulty associated with the said task thereby offers an inherent qualitative measure. This qualitative information quantized by the degree of difficulty is stored together with other quantitative results. The use of degree of difficulty has particular relevance in rehabilitation.
These and other advantages and features of the subject invention will become apparent from the detailed description of the invention that follows.